NCAFM2023 Programme Booklet

Wednesday 0940 - 1000

ZIGZAG GRAPHENE NANORIBBONS WITH PERIODIC PORPHYRIN EDGE EXTENSIONS

Feifei Xiang 1 , Yanwei Gu 2 , Amogh Kinikar 1 , Nicolo Bassi 1 , Andres Ortega 1 , Kristjan Eimre 1 , Carlo A. Pignedoli 1 , Klaus Müllen 2 , Pascal Ruffieux 1 , Roman Fasel 1* 1 nanotech@surfaces Laboratory, Empa − Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland 2 Department of Synthetic Chemistry, Max Planck Institute for Polymer Research, 55021 Mainz, Germany Email: feifei.xiang@empa.ch Graphene nanoribbons (GNRs) are a versatile nanomaterials platform with widely tunable band gaps that give rise to desirable electrical, optical, and magnetic properties [1]. GNRs with zigzag edges (ZGNRs) are of particular interests due to their potential for edge-localized electronic states and spin polarization. Atomically precise GNRs can be synthesized bottom-up using molecular precursors [2-3], allowing for extensive modification with heteroatom doping or functional groups such as chromophores or stable free radicals [4]. Porphyrin moieties, with unique optoelectronic properties, rich redox chemistry, and long-range charge transport ability, are particularly noteworthy in this context. Moreover, porphyrins offer the additional advantage of allowing the incorporation of metals, which complements the role of zigzag edges in adding spin degrees of freedom to GNR-based circuitry. However, connecting porphyrins to GNR backbones by single bonds restricts electronic interaction, highlighting the importance of fusing porphyrin units into GNRs with multiple bonds. Here, we report the on-surface synthesis and characterization of narrow ZGNRs that contain laterally fused porphyrin units at regular intervals along the ZGNR backbone. We demonstrate that this design leads to profound changes in the electronic band structure and allows for the site-selective introduction of metal centers. This work paves the way towards the fabrication of GNR based spin chains that combine both d- and π-electron spins [5], and creating tailored nanomaterials for electronic and spintronic applications.

Fig. Non-contact atomic force microscopy image of a gold-doped porphyrin-ZGNR hybrid.

References [1] H. Wang et al., Nat. Rev. Phys., 2021, 3 , 791–802. [2] J. Cai et al., Nature, 2010, 466 , 470–473. [3] P. Ruffieux et al., Nature, 2016, 531 , 489–492. [4] F. Lombardi et al., Science, 2019, 366 , 1107–1110. [5] Q. Sun et al., Adv. Sci., 2022, 9 , 2105906.

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